The present invention relates to an electronic plug-in module with a circuit board, a front plate and a mounting device for accommodation in a module rack with a mounting rail, as well as to a mounting device for mounting a front plate on a module rack and to a method for mounting a plug-in module.
For electronic equipment of modular construction such as module racks, it is common to design individual modules in the form of plug-in modules. The modules usually have a multipole connector on their back side that is inserted into a plug receptacle on the backplane of the module rack. On their front side, the plug-in modules usually have a front plate that is flush with the front side of the module rack. The module groups run in guiderails of the module rack, and are inserted into the module rack and pulled out of it in this manner.
In order to hold the plug-in modules in position, they are fixed by appropriate means on a module rack to prevent unintended loosening. In the usual locking of the plug-in modules by means of screws or snap buckles, the back side of the plug-in modules front plate stops at a mounting plane. For example, the plug-in modules are screwed into a mounting rail of the module rack with a screw through the front plate. In this case, the front plate is pressed by means of the screw towards the module rack until the front plate rests against a mounting rail that has the threads or a thread channel for the mounting screws.
Leveraging plug-in modules into a module rack by means of a lever latch handle is also known. The levers can be secured by a variety of mechanisms against unintended pivoting and, therefore, an unintended detachment of the plug-in module.
A new form of plug-in modules, which are primarily employed in modern telecommunications systems, is designed according to a standard (AMC standard, Advanced Mezzanine Card standard) developed by the PICMG (PCI Industrial Manufacturers Group). Plug-in modules according to this specification are relatively small in comparison to 19″ modules and have a front plate having a U-shaped cross section mounted at the front of the circuit board. At their rear end, the cards have a plug-in edge (card edge).
In the new plug-in modules, however, the previously familiar mounting flange with locking elements is lacking, since the modules are to be inserted into so-called carriers (adapters) that have no corresponding mounting plane or mounting rail. The depth stopping of the modules inside the carriers is accomplished by means of the rear edge of the circuit board at the base of the carrier's plug casing. The depth stop is required for a secure contact transfer of the individual contact rows of the plug connector. The locking mechanism of the modules specified by the standard secures their final position.
Because of the tolerances established and allowed in the standard for the individual components, especially for the plug-in modules and the module racks, it is not possible to provide mounting flanges on the front plate that stop against a mounting rail of the module rack and, in this way, simultaneously assure the contacting of the plug-in module with its rear edge. For instance, screwing the front plate to the module rack would have the effect of exertion of excessive pressure by the integrated plug of the plug-in module on the plug casing of the module rack. This could cause destruction.
Previously known locking systems for such plug-in modules with card edge systems are described in EP 06008996.8 for example. Due to the increased burdens with regard to shock and vibration resistance that are currently established in the standards, the mounting systems are reaching their limits. The obvious suggestion of screwing the front plate to the mounting rails of the module rack is out of the running due to the tolerance equalization required. As already mentioned above, mounting with mounting screws would lead to strains on the circuit board and cause malfunctioning.